Systems and methods for enhancing target detection

ABSTRACT

A system for determining a spatial disposition or a characteristic of a target external to a terrestrial vehicle is provided. The system may comprise a radar antenna array configured to transmit and receive radar signals, and a controller operatively coupled to the radar antenna array. The controller can be configured to use spatial information of the terrestrial vehicle and a spatial configuration of the radar antenna array to generate an enhanced main lobe by attenuating one or more side lobes in an effective sensitivity pattern associated with the radar antenna array or enhancing a main lobe in the effective sensitivity pattern associated with the radar antenna array. The controller can be configured to use the enhanced main lobe to determine (i) the spatial disposition of the target relative to the terrestrial vehicle or (ii) the characteristic of the target.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.16/451,262 filed on Jun. 25, 2019, which application is a continuationof U.S. patent application Ser. No. 16/208,442 filed on Dec. 3, 2018(issued as U.S. Pat. No. 10,371,797), which claims priority to U.S.Provisional Patent Application No. 62/675,550 filed on May 23, 2018,which application is incorporated herein by reference in its entiretyfor all purposes.

BACKGROUND

RAdio Detection And Ranging (radar) can be used in many applicationsincluding object detection, range-finding, direction-finding andmapping. Traditionally, radar has been used in aerial vehicles,satellites, and maritime vessels to locate objects and image terrain. Inrecent years, radar is finding increasing use in automobiles forapplications such as blind-spot detection, collision avoidance, andautonomous driving. Unlike optical-based sensors (such as cameras orLight Detection and Ranging (LIDAR) systems) which are affected bychanging weather and visibility, radar is capable of functioning in lowlight conditions, in the dark, and under all types of weatherconditions.

However, existing automotive radar technology may lack the requiredresolution to (1) sense different objects, (2) distinguish betweenclosely spaced objects, or (3) detect characteristics of objects on theroad or in the surrounding environment. The resolution of existingautomotive radar systems may be limited in both azimuth and elevation.Additionally, existing automotive radar systems tend to have a limitednumber of antennas and/or antenna channels, and limited aperture sizedue to constraints imposed by automotive vehicle body size.

To improve angular resolution, some detection systems may use multipleantennas. Such systems may need a large number of antennas spaced apartat a certain distance in order to achieve improved angular resolution.However, such systems often require additional components and sensorsthat are cost prohibitive for commercial automotive use. Furthermore,the total physical size of such systems may make it impractical toimplement such systems on terrestrial vehicles.

With the recent emphasis on autonomous driving, there is a need for longrange detection systems on automotive vehicles that can provide advancenotice to drivers about potential obstacles or dangers on the roads.However, existing automotive radar technology may not be ready and/orsuitable for deployment in long range detection systems on automotivevehicles, in view of at least the challenges described above.

SUMMARY

A need exists for a forward and/or rear facing high resolution radarsystem on a terrestrial vehicle that can be used to accurately detecttargets and spatial dispositions and/or characteristics of the targetsas the terrestrial vehicle is moving through an environment. A highresolution radar system as disclosed herein can be a radar systemcapable of distinguishing between multiple targets that are very closeto one another in bearing with respect to the radar system. The radarsystem may achieve higher resolution by improving azimuth resolution,elevation resolution, or any combination thereof. Azimuth resolution isthe ability of a radar system to distinguish between objects at similarrange but different bearings. Elevation resolution is the ability of aradar system to distinguish between objects at similar range butdifferent elevation. Azimuth and elevation resolution may be a functionof radar array geometry. The radar system can accurately detect targetsand/or characteristics of targets if it can sense the presence of one ormore targets, distinguish one or more targets as separate targets,and/or determine some physical properties of one or more targets.

The systems and methods disclosed herein can be implemented using anyradar antenna array (for example, a millimeter wavelength radar antennaarray that is relatively low cost, compact and readily commerciallyavailable). The radar systems disclosed herein can have an angularresolution that enables accurate measurement and tracking of vehicleposition using returns from the radar antenna array. The radar antennaarray may be a sparse antenna array. The sparse antenna array may havemultiple antennas that are spaced further apart than the antennas in atypical fully-sampled array, where adjacent antenna elements areseparated by at most one-half of a wavelength of the radar signalstransmitted and/or received by the radar system. If adjacent antennas ina fully-sampled array are separated by more than about one-half of awavelength of the radar signals, the radar systems may exhibit aliasingside lobes in its directional response. An aliasing side lobe may be apeak in the radar system's directional response which may notnecessarily correspond to a true physical location of a target. Thesystems and methods disclosed herein may improve the angular resolutionof a radar system with a sparse antenna array by suppressing aliasingside lobes in the sparse antenna array radar system's directionalresponse. By minimizing aliasing sidelobes generated by a sparse antennaarray, the systems and methods disclosed herein can achieve a similarresolution with a sparse antenna array as a fully-sampled array whileusing fewer radar antennas.

In an aspect, the present disclosure provides systems and methods fordetermining a spatial disposition or a characteristic of a targetexternal to a terrestrial vehicle. The system may comprise a radarantenna array and at least one controller operatively coupled to theradar antenna array. The radar antenna array may be mountable on aterrestrial vehicle. The radar antenna array may be configured totransmit successive radar pulses and receive a plurality of signalscorresponding to at least a subset of the successive radar pulses. Theplurality of signals may be generated upon the at least a subset of thesuccessive radar pulses interacting with the target. An effectivesensitivity pattern may be obtained from the plurality of signals. Theeffective sensitivity pattern may be associated with the radar antennaarray. The effective sensitivity pattern may comprise a main lobe and aside lobe. The side lobe may comprise an aliasing side lobe. The atleast one controller may be operatively coupled to the radar antennaarray. The at least one controller may be configured to use spatialinformation of the terrestrial vehicle while the terrestrial vehicle isin motion and a spatial configuration of the radar antenna array toprovide an enhanced main lobe. The enhanced main lobe may be provided byattenuating the side lobe relative to the main lobe or by enhancing themain lobe relative to the side lobe. The controller may be configured touse the enhanced main lobe to determine the spatial disposition orcharacteristic of the target.

In some embodiments, the radar antenna array may comprise a transmittingantenna and a receiving antenna. In some embodiments, the radar antennaarray may comprise a virtual antenna. In some embodiments, the radarantenna array may be configured to be mounted on the terrestrial vehiclein a forward-facing direction or in a reverse-facing direction relativeto the direction of motion of the terrestrial vehicle.

In some embodiments, the spatial configuration of the radar antennaarray may be based at least in part on an imaging region and an angularresolution with a field of detection of the radar antenna array. In someembodiments, an aperture size of the radar antenna array may be based atleast in part on the angular resolution and an operating wavelength ofthe radar antenna array. In some embodiments, the at least onecontroller may be configured to use the angular resolution and theoperating wavelength of the radar antenna array at least in part todefine a distance traveled by the terrestrial vehicle. In someembodiments, the side lobe in an effective sensitivity pattern may belocated at an angular distance from the main lobe in an effectivesensitivity pattern. In some embodiments, the spatial configuration ofthe radar antenna array may comprise a spacing between adjacent antennasof the radar antenna array such that the angular distance may be greaterthan the imaging region. In some cases, the adjacent antennas of theradar antenna array may be distributed at a spacing such that the sidelobe lies outside of the imaging region. In some cases, the imagingregion may be defined separately for azimuth and elevation angles. Insome cases, the imaging region may cover at least ±10 degrees from aforward or reverse direction of motion of the terrestrial vehicle. Insome cases, the imaging region may cover no more than ±60 degrees from aforward or reverse direction of motion of the terrestrial vehicle.

In some embodiments, the spatial information of a terrestrial vehiclemay comprise a distance travelled by the terrestrial vehicle. Thespatial configuration of the radar antenna array may comprise a spacingbetween adjacent antennas of the radar antenna array. The controller maybe configured to attenuate the side lobe relative to the main lobe or toenhance the main lobe relative to the side lobe to provide an enhancedmain lobe. The controller may be configured to provide an enhanced mainlobe based at least in part on the distance travelled by the terrestrialvehicle and the spacing between adjacent antennas of the radar antennaarray.

In some embodiments, the spatial configuration of the radar antennaarray may comprise a spacing between adjacent antennas of the radarantenna array. The spacing may be greater than one-half of an operatingwavelength of the radar antenna array. In some cases, the spacing may beat least 10% greater than one-half of the operating wavelength of theradar antenna array. In some cases, the spacing may be greater thanabout 2 millimeters.

In some embodiments, the radar antenna array may be configured totransmit successive radar pulses at a pulse repetition frequency suchthat when the terrestrial vehicle is in motion, a change in position ofthe terrestrial vehicle between two successive radar pulses may be fromabout one-quarter to about six times an operating wavelength of theradar antenna array. In some cases, the change in position of theterrestrial vehicle between two successive radar pulses may be less thanabout one-half of the operating wavelength of the radar antenna array.

In some embodiments, the at least one controller may be configured toobtain position information of the terrestrial vehicle using a vehicleposition sensor. The vehicle position sensor may comprise at least onemember selected from the group consisting of an inertial measurementunit, a global positioning system sensor, a camera, a light detectionand ranging unit, a wheel encoder, and a radar. In some cases, thevehicle position sensor may be located separately from the radar antennaarray. The vehicle position sensor may be configured to be mounted tothe terrestrial vehicle.

In some embodiments, the at least one controller may be configured todetermine spatial dispositions or characteristics of a plurality oftargets by attenuating the plurality of side lobes associated with theplurality of targets or by enhancing a plurality of main lobesassociated with the plurality of targets to provide a plurality ofenhanced main lobes. The plurality of targets may comprise the target.In some cases, the at least one controller may be configured todifferentiate between the spatial dispositions or characteristics of theplurality of targets after the plurality of side lobes have beenattenuated or the plurality of main lobes have been enhanced.

In some embodiments, the system may be configured to perform a methodfor identifying a position of a target. The method may comprisecollecting radar data from an environment external to the terrestrialvehicle using a radar antenna array mounted on the terrestrial vehicle.The radar data may comprise a main lobe and a side lobe. The side lobemay be an aliasing side lobe. The method may further comprise collectingposition information of the terrestrial vehicle. The method may furthercomprise using at least the position information to attenuate the sidelobe relative to the main lobe or to enhance the main lobe relative tothe side lobe to yield an enhanced main lobe. The method may furthercomprise using the enhanced main lobe to identify the position of thetarget in the environment at a detection accuracy of at least 90%. Thetarget may have a size of at least 0.2 meters. The target may be locatedat a distance of at least 1 meter from the terrestrial vehicle. In somecases, the radar antenna array may be provided on a front side of theterrestrial vehicle in a forward-facing direction of the terrestrialvehicle. In some cases, the radar antenna array may be provided on arear side of the terrestrial vehicle in a rear-facing direction of theterrestrial vehicle.

In some cases, the system may be configured to perform a method fordetermining a spatial disposition or characteristic of a target. Themethod may comprise providing a radar antenna array on a terrestrialvehicle. The method may further comprise transmitting successive radarpulses and receiving a plurality of signals corresponding to at least asubset of the successive radar pulses with the aid of the radar antennaarray. The plurality of signals may be generated upon the at least asubset of the successive radar pulses interacting with the target. Aneffective sensitivity pattern associated with the radar antenna arraymay be obtainable from the plurality of signals. The effectivesensitivity pattern may comprise a main lobe and a side lobe. The sidelobe may comprise an aliasing side lobe. The method may further compriseusing position information of the terrestrial vehicle while the vehicleis in motion and a spatial configuration of the radar antenna array toprovide an enhanced main lobe. The enhanced main lobe may be provided byusing position information of the terrestrial vehicle while the vehicleis in motion and a spatial configuration of the radar antenna array toattenuate the side lobe relative to the main lobe or to enhance the mainlobe relative to the side lobe. The method may further comprise usingthe enhanced main lobe to determine the spatial disposition orcharacteristic of the target. In some cases, the spatial disposition orcharacteristic of the target may be determined substantially in realtime while the terrestrial vehicle is in motion relative to the target.In some cases, the radar antenna array may be mounted on the terrestrialvehicle in a forward-facing direction relative to the direction ofmotion of the terrestrial vehicle. In some cases, the radar antennaarray may be mounted on the terrestrial vehicle in a rear-facingdirection relative to the direction of motion of the terrestrialvehicle. In some cases, the spatial configuration of the radar antennaarray may comprise a spacing between adjacent antennas of the radarantenna array. The spacing may be greater than one-half of an operatingwavelength of the radar antenna array. In some cases, the method mayfurther comprise determining spatial dispositions or characteristics ofa plurality of targets by attenuating a plurality of sidelobesassociated with the plurality of targets or by enhancing a plurality ofmain lobes associated with the plurality of targets, to provide aplurality of enhanced main lobes. The plurality of targets may comprisethe target. In some cases, the method may further comprisedifferentiating between the spatial dispositions or characteristics ofthe plurality of targets after the plurality of side lobes have beenattenuated or the plurality of main lobes have been enhanced.

Additional aspects and advantages of the present disclosure will becomereadily apparent to those skilled in this art from the followingdetailed description, wherein only illustrative embodiments of thepresent disclosure are shown and described. As will be realized, thepresent disclosure is capable of other and different embodiments, andits several details are capable of modifications in various obviousrespects, all without departing from the disclosure. Accordingly, thedrawings and description are to be regarded as illustrative in nature,and not as restrictive.

INCORPORATION BY REFERENCE

All publications, patents, and patent applications mentioned in thisspecification are herein incorporated by reference to the same extent asif each individual publication, patent, or patent application wasspecifically and individually indicated to be incorporated by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity inthe appended claims. A better understanding of the features andadvantages of the present invention will be obtained by reference to thefollowing detailed description that sets forth illustrative embodiments,in which the principles of the invention are utilized, and theaccompanying drawings of which:

FIG. 1A illustrates a system that can be used on a vehicle to detect oneor more targets in a surrounding environment, in accordance with someembodiments.

FIG. 1B illustrates one or more controllers operatively coupled to aradar antenna array, in accordance with some embodiments.

FIG. 2A illustrates a radar antenna array, in accordance with someembodiments.

FIG. 2B illustrates a radar antenna array with a spatial configurationand a field of detection, in accordance with some embodiments

FIG. 3A illustrates an effective sensitivity pattern of a radar antennaarray, in accordance with some embodiments.

FIG. 3B illustrates an effective sensitivity pattern with an enhancedmain lobe, in accordance with some embodiments.

FIG. 4 illustrates an effective sensitivity pattern with an angulardistance between a main lobe and a side lobe, in accordance with someembodiments.

FIG. 5 illustrates a controller operatively coupled to a radar antennaarray and a vehicle position sensor, in accordance with someembodiments.

FIG. 6 illustrates an effective sensitivity pattern with one or moreenhanced main lobes, in accordance with some embodiments.

FIG. 7 illustrates a computer control system that is programmed orotherwise configured to implement methods provided herein.

DETAILED DESCRIPTION

While various embodiments of the present disclosure have been shown anddescribed herein, it will be obvious to those skilled in the art thatsuch embodiments are provided by way of example only. Numerousvariations, changes, and substitutions may occur to those skilled in theart without departing from the present disclosure. It should beunderstood that various alternatives to the embodiments of the presentdisclosure described herein may be employed.

The term “terrestrial vehicle,” as used herein, generally refers to avehicle that is configured to operate by contacting the ground or at alocation below the ground. In some examples, the terrestrial vehicle isa car, bus, train, truck, bicycle, motorcycle, scooter, boat, submarine,or any transportation device for use on the ground. The terrestrialvehicle can be a car. The terrestrial vehicle can be any machinery thatnormally operates by contacting the ground or operating below ground,such as, for example, a robot for ground use. The terrestrial vehiclemay not be capable of operating in the air or in space. For example, theterrestrial vehicle may not be a plane or a helicopter.

Whenever the term “at least,” “greater than,” or “greater than or equalto” precedes the first numerical value in a series of two or morenumerical values, the term “at least,” “greater than” or “greater thanor equal to” applies to each of the numerical values in that series ofnumerical values. For example, greater than or equal to 1, 2, or 3 isequivalent to greater than or equal to 1, greater than or equal to 2, orgreater than or equal to 3.

Whenever the term “no more than,” “less than,” or “less than or equalto” precedes the first numerical value in a series of two or morenumerical values, the term “no more than,” “less than,” or “less than orequal to” applies to each of the numerical values in that series ofnumerical values. For example, less than or equal to 3, 2, or 1 isequivalent to less than or equal to 3, less than or equal to 2, or lessthan or equal to 1.

The present disclosure provides systems and methods that can improvedetection of objects from terrestrial vehicles. Existing automotiveradar technology may lack the required resolution to (1) sense differentobjects, (2) distinguish between closely spaced objects, or (3) detectcharacteristics of objects on the road or in the surroundingenvironment. Furthermore, existing automotive radar systems tend to havea limited number of antennas and/or antenna channels and limitedaperture size due to constraints imposed by automotive vehicle bodysize. The systems and methods disclosed herein can improve theresolution of a radar-based target detection system on a terrestrialvehicle, for example, by using vehicle position information and aSynthetic Aperture Radar to suppress aliasing sidelobes that may begenerated in the directional response of a sparse antenna array. A SARsystem as disclosed herein can provide high resolution radar imageryfrom a moving terrestrial platform or terrestrial vehicle by using themotion path of the platform or vehicle to simulate a large antenna oraperture electronically and/or virtually.

A typical radar system may comprise a fully-sampled radar antenna array.A fully-sampled radar antenna array may be a radar antenna arrayconfigured such that adjacent antenna elements are separated by at mostone-half of a wavelength of the radar signals transmitted and/orreceived by the radar system. If adjacent antennas are separated by morethan about one-half of a wavelength of the radar signals, the radarsystem may exhibit aliasing side lobes in its directional response. Analiasing side lobe may be a peak in a radar system's directionalresponse which may not correspond to a true physical location of atarget. A sparse antenna array radar system may be a radar system thatcomprises a sparse antenna array. A sparse antenna array may be a radarantenna array with multiple antennas that are spaced further apart thanthe antennas in a typical fully-sampled array. The systems and methodsdisclosed herein may improve the angular resolution of a sparse antennaarray radar system by suppressing aliasing side lobes in the sparseantenna array radar system's directional response. By minimizingaliasing sidelobes generated by the sparse antenna array radar system,the systems and methods disclosed herein can achieve a similarresolution with a sparse antenna array as a fully-sampled array whilealso using fewer radar antennas.

FIG. 1A shows a system 100 that may be used on a vehicle 104 todetermine a spatial disposition or characteristic of one or more targets102 in a surrounding environment 101. The system may be mounted to anyside of the vehicle, or to one or more sides of the vehicle, e.g. afront side, rear side, lateral side, top side, or bottom side of thevehicle. In some cases, the system may be mounted between two adjacentsides of the vehicle. The system may be oriented to detect one or moretargets in front of the vehicle, behind the vehicle, or to the lateralsides of the vehicle.

The system may comprise any one or more elements of a conventional radarsystem, a phased array radar system, an AESA (Active ElectronicallyScanned Array) radar system, a synthetic aperture radar (SAR) system, aMIMO (Multiple-Input Multiple-Output) radar system, and/or a phased-MIMOradar system. A conventional radar system may be a radar system thatuses radio waves transmitted by a transmitting antenna and received by areceiving antenna to detect objects. A phased array radar system may bea radar system that manipulates the phase of one or more radio wavestransmitted by a transmitting and receiving module and uses a pattern ofconstructive and destructive interference created by the radio wavestransmitted with different phases to steer a beam of radio waves in adesired direction. An AESA radar system may be a phased array radarsystem that uses one or more transmitting and receiving modules toproduce one or more beams of radio waves at different phases and/orfrequencies. A synthetic aperture radar system may be a phased arrayradar system that uses a single antenna to combine multiple raw radarreturns from different geometric positions into coherent focused images.A MIMO radar system may be a radar system that uses multipletransmitting antennas to transmit one or more signals independently ofother transmitting antennas and multiple receiving antennas to receivethe one or more signals transmitted by the transmitting antennasindependently of other receiving antennas. A phased-MIMO radar systemmay be a radar system comprising one or more components or features of aphased array radar system or a MIMO radar system.

The methods and systems disclosed herein may be applied to any suitableterrestrial vehicle. A terrestrial vehicle may be a motor vehicle or anyother vehicle that uses a source of energy, renewable or nonrenewable,(solar, thermal, electrical, wind, petroleum, etc.) to move across or inclose proximity to the ground (within 1 meter, 2 meter, 3 meter, etc.).The terrestrial vehicle may be a self-driving vehicle or may be operatedby a living subject, such as a human or animal. The terrestrial vehiclemay be stationary, moving, or capable of movement.

The methods and systems disclosed herein may be applied to any suitableaerial vehicle. An aerial vehicle may be a motor vehicle or any othervehicle that uses a source of energy, renewable or nonrenewable, (solar,thermal, electrical, wind, petroleum, etc.) to move through the air orthrough space. The aerial vehicle may be a self-driving vehicle or maybe operated by a living subject, such as a human or animal. The aerialvehicle may be stationary, moving, or capable of movement.

The methods and system disclosed herein may be applied to any suitableaquatic vehicle. An aquatic vehicle may be a motor vehicle or any othervehicle that uses a source of energy, renewable or nonrenewable, (solar,thermal, electrical, wind, petroleum, etc.) to move across or throughwater. The aquatic vehicle may be a self-driving vehicle or may beoperated by a living subject, such as a human or animal. The aquaticvehicle may be stationary, moving, or capable of movement.

The vehicle may be a land-bound vehicle. The vehicle may travel overland. Alternatively or in addition, the vehicle may be capable oftraveling on or in water, underground, in the air, and/or in space. Thevehicle may be an automobile. The vehicle may be a land-bound vehicle,watercraft, aircraft, and/or spacecraft. The vehicle may travel freelyover a surface. The vehicle may travel freely within two or moredimensions. The vehicle may primarily drive on one or more roads.

Optionally, the vehicle may be an unmanned vehicle. The vehicle may nothave a passenger or operator on-board the vehicle. The vehicle may ormay not have a space within which a passenger could ride. The vehiclemay or may not have space for cargo or objects to be carried by thevehicle. The vehicle may or may not have tools that may permit thevehicle to interact with the environment (e.g., collect samples, moveobjects). The vehicle may or may not have objects that may be emitted tobe dispersed to the environment (e.g., light, sound, liquids,pesticides). The vehicle may operate without requiring a human operator.

In some embodiments, the vehicle may permit one or more passengers toride on-board the vehicle. The vehicle may comprise a space for one ormore passengers to ride the vehicle. The vehicle may have an interiorcabin with space for one or more passengers. The vehicle may or may nothave an operator. For example, a vehicle may have a space for a driverof the vehicle. In some embodiments, the vehicle may be capable of beingdriven by a human operator. Alternatively or in addition, the vehiclemay be operated using an autonomous driving system.

In some embodiments, a vehicle may switch between a manual driving modeduring which a human driver would drive the vehicle, and an autonomousdriving mode during which an automated controller may generate signalsthat operate the vehicle without requiring intervention of the humandriver. In some embodiments, the vehicle may provide driver assistancewhere the driver may primarily manually drive the vehicle, but thevehicle may execute certain automated procedures or assist the driverwith performing certain procedures (e.g., lane changes, merging,parking, auto-braking). In some embodiments, the vehicle may have adefault operation mode. For example, the manual driving mode may be adefault operation mode, or an autonomous driving mode may be a defaultoperation mode.

A target may be any object external to the vehicle. A target may be aliving being or an inanimate object. A target may be a pedestrian, ananimal, a vehicle, a building, a sign post, a sidewalk, a sidewalk curb,a fence, a tree, or any object that may obstruct a vehicle travelling inany given direction. A target may be stationary, moving, or capable ofmovement.

A target may be located in the front, rear, or lateral side of thevehicle. A target may be positioned at a range of about 1, 2, 3, 4, 5,10, 15, 20, 25, 50, 75, or 100 meters from the vehicle. A target may belocated on the ground, in the water, or in the air. A target may beoriented in any direction relative to the vehicle. A target may beorientated to face the vehicle or oriented to face away from the vehicleat an angle ranging from 0 to 360 degrees. In some embodiments, a targetmay comprise multiple targets external to a terrestrial vehicle.

A target may have a spatial disposition or characteristic that may bemeasured or detected. Spatial disposition information may includeinformation about the position, velocity, acceleration, and otherkinematic properties of the target relative to the terrestrial vehicle.A characteristic of a target may include information on the size, shape,orientation, and material properties, such as reflectivity, of thetarget.

In some embodiments, a target may have a size of at least 0.2 meters, bein a side facing direction of a terrestrial vehicle, and be at leastabout 1 meter from a terrestrial vehicle. In some embodiments, a targetmay have a size of at least 0.2 meters, be in a forward or rear facingdirection of a terrestrial vehicle, and be at least about 1 meter from aterrestrial vehicle.

A surrounding environment may be a location and/or setting in which thevehicle may operate. A surrounding environment may be an indoor oroutdoor space. A surrounding environment may be an urban, suburban, orrural setting. A surrounding environment may be a high altitude or lowaltitude setting. A surrounding environment may include settings thatprovide poor visibility (night time, heavy precipitation, fog,particulates in the air). A surrounding environment may include targetsthat are on a travel path of a vehicle. A surrounding environment mayinclude targets that are outside of a travel path of a vehicle. Asurrounding environment may be an environment external to a vehicle.

As illustrated in FIG. 1B, system 100 may include a radar antenna array110 and one or more controllers 130-1, 130-2, 130-3. The one or morecontrollers may be operatively coupled to the radar antenna array. Thecontroller may be implemented onboard the terrestrial vehicle 104 oroff-site on a server. The controller may comprise a computer processor,application specific integrated circuit, a graphics processing unit, ora field programmable gate array.

FIG. 2A shows a radar antenna array 110. The radar antenna array maycomprise a conventional radar system, a phased array radar system, anAESA (Active Electronically Scanned Array) radar system, a syntheticaperture radar (SAR) system, a MIMO (Multiple-Input Multiple-Output)radar system, or a phased-MIMO radar system. A conventional radar systemmay be a radar system that uses radio waves transmitted by atransmitting antenna and received by a receiving antenna to detectobjects. A phased array radar system may be a radar system thatmanipulates the phase of one or more radio waves transmitted by atransmitting and receiving module and uses a pattern of constructive anddestructive interference created by the radio waves transmitted withdifferent phases to steer a beam of radio waves in a desired direction.An AESA radar system may be a phased array radar system that uses one ormore transmitting and receiving modules to produce one or more beams ofradio waves at different phases and/or frequencies. A synthetic apertureradar system may be a phased array radar system that uses a singleantenna to combine multiple raw radar returns from different geometricpositions into coherent focused images. A MIMO radar system may be aradar system that uses multiple transmitting antennas to transmit asignal independently of other transmitting antennas and multiplereceiving antennas to receive the one or more signals transmitted by thetransmitting antennas independently of other receiving antennas. Aphased-MIMO radar system may be a radar system comprising one or morecomponents or features of a phased array radar system or a MIMO radarsystem.

The radar antenna array may be configured to be mounted to a front side,rear side, or lateral side of a terrestrial vehicle. The radar antennaarray may be mounted to any side of the vehicle, or to one or more sidesof the vehicle, e.g. a front side, rear side, lateral side, top side,and/or bottom side of the vehicle. In some cases, the radar antennaarray may be mounted between two or more adjacent sides of the vehicle.

The radar antenna array may be configured to transmit one or more radarpulses. A radar pulse may be any electromagnetic wave transmitted by theradar antenna array within a frequency range of about 1 Hz to about 300GHz. The one or more radar pulses may be successive radar pulsestransmitted repeatedly by the radar antenna array at a pre-definedfrequency.

The successive radar pulses may be transmitted at a pre-definedfrequency equal to a pulse repetition frequency. A pulse repetitionfrequency may be a rate at which the radar antenna array repeatedlytransmits the successive radar pulses. The pulse repetition frequencymay be less than or equal to 9 KHz. The pulse repetition frequency maybe greater than 9 KHz. The pulse repetition frequency may be 1 KHz, 2KHz, 3 KHz, 4 KHz, 5 KHz, 6 KHz, 7 KHz, 8, KHz, 9 KHz, or any valuebetween 1 KHz and 9 KHz. In some embodiments, the pulse repetitionfrequency may preferably range from about 7 KHz to about 9 KHz. Thepulse repetition frequency of the radar system may be designed based onmaximum vehicle speed. The pulse repetition frequency may be designed sothat the time between successive radar pulses corresponds to a vehicletravel distance that is less than a value S. S may be less than 1.5 mmor greater than 2 mm. S may be equal to 1.5 mm or equal to 2 mm. S maybe greater than or equal to 1.5 mm. S may be less than or equal to 2 mm.S may 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2 mm, or any value between1.5 mm and 2 mm.

The radar antenna array may be configured to receive a plurality ofsignals. The plurality of signals may be a subset of the successiveradar pulses that are transmitted by the radar antenna array andreflected back to the radar antenna array after interacting withexternal targets.

As illustrated in FIG. 2A, the radar antenna array 110 may include atransmitting antenna 112 and a receiving antenna 114. In someembodiments, the radar antenna array may include one or moretransmitting antennas 112-1, 112-2 and/or one or more receiving antennas114-1, 114-2. The radar antenna array may be used to detect one or moretargets 102 in a surrounding environment 101.

A transmitting antenna may be any antenna (dipole, directional, patch,sector, Yagi, parabolic, grid) that can convert electrical signals intoelectromagnetic waves and transmit the electromagnetic waves. In someembodiments, one or more transmitting antennas may be used to transmitone or more radar pulses. A radar pulse may be any electromagnetic wavetransmitted by the transmitting antenna within a frequency range ofabout 1 Hertz (Hz) to about 300 GigaHertz (GHz). The one or more radarpulses may be successive radar pulses transmitted repeatedly by the oneor more transmitting antennas at a pre-defined frequency.

As illustrated in FIG. 2A, the successive radar pulses 105 may have acenter frequency f₀. A center frequency may be an arithmetic orgeometric mean of a lower and upper cutoff frequency of a radar system.A cutoff frequency may be an upper or lower boundary in a radar system'sfrequency response at which signal attenuation begins to increaserapidly. The cutoff frequency may be defined as the frequency at whichthe ratio of power output to power input has a magnitude of about 0.707.The successive radar pulses may have a wavelength associated with thecenter frequency of the successive radar pulses transmitted by atransmitting antenna.

The one or more radar pulses may be transmitted at a pre-definedfrequency equal to a pulse repetition frequency. A pulse repetitionfrequency may be a rate at which one or more transmitting antennasrepeatedly transmit the successive radar pulses. The pulse repetitionfrequency may be less than or equal to 9 KHz. The pulse repetitionfrequency may be greater than 9 KHz. The pulse repetition frequency maybe at least about 1 KHz, 2 KHz, 3 KHz, 4 KHz, 5 KHz, 6 KHz, 7 KHz, 8,KHz, 9 KHz, or any value between 1 KHz and 9 KHz. In some embodiments,the pulse repetition frequency may preferably range from about 7 KHz toabout 9 KHz. The pulse repetition frequency of the radar system may bedesigned based on maximum vehicle speed. The pulse repetition frequencymay be designed so that the time between successive radar pulsescorresponds to a vehicle travel distance that is less than a value S. Smay be less than 1.5 millimeter (mm) or greater than 2 mm. S may beequal to 1.5 mm or equal to 2 mm. S may be greater than or equal to 1.5mm. S may be less than or equal to 2 mm. S may be at least about 1.5 mm,1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2 mm, or any value between 1.5 mm and 2mm. In some cases, S may be equal to about one-half of a wavelengthcorresponding to the center frequency f₀ of the successive radar pulses.In some cases, the pulse repetition frequency may be chosen such thatthe distance travelled by a terrestrial vehicle is less than aboutone-half a wavelength corresponding to the center frequency of thesuccessive radar pulses.

A receiving antenna may be any antenna (dipole, directional, patch,sector, Yagi, parabolic, grid) that can receive electromagnetic wavesand convert the radiofrequency radiation waves into electrical signals.The receiving antenna may be used to receive a subset of the successiveradar pulses that are transmitted by the transmitting antenna andreflected back to the receiving antenna after interacting with externaltargets. In some embodiments, one or more receiving antennas may be usedto receive a subset of the successive radar pulses that are transmittedby one or more transmitting antennas and reflected back to the one ormore receiving antennas after interacting with external targets.

The radar antenna array may have a spatial configuration. The spatialconfiguration may involve a fixed position, a fixed orientation, or acombination of either a fixed position and/or a fixed orientation. Theradar antenna array may have a fixed position relative to one or moresides of a terrestrial vehicle. The radar antenna array may beconfigured to be mounted to a front side, rear side, or lateral side ofa terrestrial vehicle. The radar antenna array may be mounted to anyside of the vehicle, or to one or more sides of the vehicle, e.g. afront side, rear side, lateral side, top side, and/or bottom side of thevehicle. In some cases, the radar antenna array may be mounted betweentwo or more adjacent sides of the vehicle. The radar antenna array mayhave a fixed orientation relative to the path of motion of a vehicle.The radar antenna array may be oriented in any direction from 0 degreesto 360 degrees in azimuth angle and/or elevation angle relative to thepath of motion of a vehicle. In some embodiments, the radar antennaarray may be configured to be mounted in a forward-facing directionrelative to the direction of motion of a terrestrial vehicle. In otherembodiments, the radar antenna array may be configured to be mounted ina reverse-facing direction relative to the direction of motion of aterrestrial vehicle.

In some embodiments, the spatial configuration of the radar antennaarray may involve a fixed spatial configuration between adjacenttransmitting and/or receiving antennas in a radar antenna array. Theradar antenna array may comprise a transmitting antenna and a receivingantenna arranged in a fixed spatial configuration relative to oneanother. In some embodiments, the transmitting and receiving antenna maybe arranged so that they are in the same plane. In other embodiments,the transmitting and receiving antenna may or may not be onsubstantially the same plane. For example, the transmitting antenna maybe on a first plane and the receiving antenna may be on a second plane.The first plane and second plane may be parallel to one another.Alternatively, the first and second planes need not be parallel, and mayintersect one another. In some cases, the first plane and second planemay be perpendicular to one another.

The transmitting and receiving antenna may or may not be at the sameelevation above ground or at different elevations above ground. Theretransmitting and receiving antenna may or may not have a vertical orhorizontal degree of orientation. A vertical degree of orientation maybe less than or equal to about 90 degrees, 80 degrees, 70 degrees, 60degrees, 50 degrees, 40 degrees, 30 degrees, 20 degrees, 10 degrees, 5degrees, 3 degrees, or 1 degree. A horizontal degree of orientation maybe less than or equal to about 90 degrees, 80 degrees, 70 degrees, 60degrees, 50 degrees, 40 degrees, 30 degrees, 20 degrees, 10 degrees, 5degrees, 3 degrees, or 1 degree.

The transmitting and receiving antenna may be arranged to have the samevertical degree of orientation. For instance, the transmitting andreceiving antenna may be arranged with zero degrees of verticalorientation. In another example, the transmitting and receiving antennamay be angled slightly upwards, or may be angled slightly downwards.Alternatively, the transmitting and receiving antenna may have slightlydifferent vertical orientations. For example, one transmitting and/orreceiving antenna may be angled slightly upwards, while the othertransmitting and/or receiving antenna may be angled slightly downwardsor straight horizontally. In some embodiments, the transmitting andreceiving antenna may have slightly different horizontal and/or verticalorientations or substantially different horizontal and/or verticalorientations. The variations in horizontal and/or vertical orientationsmay allow the system to detect different objects of various heights(e.g., children who may be below a certain height and not easilydetected, small animals such as pets, bicycles, motorcycles, trucks suchas 18-wheelers, trucks with tailgates, etc.).

In some cases, a transmitting antenna may be aligned in a firstdirection and a receiving antenna may be aligned in a second direction.An angle between the first direction and the second direction may rangefrom 0 degrees to 360 degrees in the XY plane, the XZ plane, or the YZplane. The angle between the first direction and second direction may be0 degrees, 45 degrees, 90 degrees, 135 degrees, 180 degrees, 225degrees, 270 degrees, 315 degrees, 360 degrees, or any value between 0degrees and 360 degrees. Alternatively, a transmitting antenna may belocated on a first plane and a receiving antenna may be located on asecond plane, and the first plane and second plane may be distinctplanes that are not parallel or perpendicular to each other.

As illustrated in FIG. 2B, the spatial configuration of a radar antennaarray 110 may also involve a relative fixed distance d between thetransmitting antenna 112 and the receiving antenna 114. The relativefixed distance may be 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9mm, 10 mm, 10 cm, 100 cm, 1 m, or any value between 1 mm and 1 m. Therelative fixed distance may have a tolerance based on a pre-definedthreshold value. The threshold value may be associated with a percentageof a wavelength of a transmitted radar pulse or a percentage of afraction of a wavelength of a transmitted radar pulse. A fraction of awavelength of a transmitted radar pulse may be less than or equal toabout 1, 0.75, 0.67, 0.5, 0.33, 0.25, 0.2, or 0.1 of the wavelength of atransmitted radar pulse. In some cases, a fraction of the wavelength ofa transmitted radar pulse may be greater than 1. For example, a fractionof the wavelength of a transmitted radar pulse may be at least about1.25, 1.5, 1.75, 2, 3, 4, 5, 6, 7, 8, 9, or 10 times the wavelength of atransmitted radar pulse. The radar antenna array may also have a fieldof detection 119. The field of detection may comprise an imaging regionas described elsewhere herein. An imaging region may be a subset of theregion encompassed by the field of detection of the radar antenna array.In some cases, the spatial configuration of the radar antenna array maybe based at least in part on the imaging region as described in moredetail later in this specification.

The fixed spatial configuration may be substantially maintained byrigidly mounting one or transmitting and/or receiving antennas to asupport structure. The support structure may keep the transmitting andreceiving antennas at fixed positions relative to one another. Movementof the vehicle may cause less than a 5 degree, 3 degree, 2 degree, 1degree, 0.5 degree or 0.1 degree variance in the angles relative to oneanother and/or relative to the environment. Such movement of less thanthe degrees provided may constitute the transmitting and/or receivingantennas being substantially fixed. The support structure may be formedfrom a substantially rigid material. In some alternative embodiments,the transmitting and receiving antennas may move relative to oneanother. During operation of the vehicle, the transmitting and receivingantennas may move relative to the vehicle body. The support structuremay comprise one or more hinges, ball joints, tracks, slides, grooves,or other mechanisms that may allow the transmitting and receivingantennas to move relative to one another. The support structure maycomprise one or more actuator that may cause the transmitting andreceiving antennas to move relative to one another. In some embodiments,the transmitting and receiving antennas may be supported by a carrier onthe support structure. The carrier may be gimbal as described elsewhereherein. The carrier may comprise a one-axis gimbal, two-axis gimbal, orthree-axis gimbal. The transmitting and receiving antennas may rotateabout a yaw, pitch, and/or roll axis relative to the support structure.In some embodiments, at some moment in time, the carrier may hold thetransmitting and receiving antennas at fixed positions relative to oneanother, the support structure, and/or the vehicle. In some embodiments,the carrier may permit movement about one, two, or more degrees offreedom relative to the support structure, vehicle, or inertialreference frame, to maintain a fixed disposition between thetransmitting and receiving antennas. The transmitting and receivingantennas may rotate about the same amount in the same direction. In someinstances, the fixed disposition may be maintained with aid of one ormore linkages. The linkages may comprise serial or parallel linkages.The linkages may be multi-bar linkages. The fixed disposition may bemaintained with aid of a kinematic coupling. The fixed disposition maybe maintained by mechanically coupling the transmitting and receivingantennas units in a rigid manner. The disposition of the transmittingand receiving antennas may be controlled in real-time. The dispositionof the transmitting and receiving antennas may be controlled duringoperation of the vehicle.

The transmitting and receiving antennas may be held within a recess orsleeve of the common support. The transmitting and receiving antennasmay be attached with aid of brackets, or other types of fasteners, tothe common support. The transmitting and receiving antennas may becompletely or partially embedded in the common support. The transmittingand receiving antennas on a common support may be located close to oneanother. In some embodiments, there may be a distance of less than 30cm, 20 cm, 15 cm, 10 cm, 7 cm, 5 cm, 3 cm, 2 cm, 1 cm, 0.5 cm, or 0.1 cmbetween adjacent transmitting and/or receiving antennas. Thetransmitting and receiving antennas may be supported by the supportstructure. The weight of the transmitting and receiving antennas may beborne by the support structure.

In some embodiments, the support structure may be built into a chassisof the vehicle or integrated into a chassis of the vehicle. The chassisof the vehicle may include an internal frame of the vehicle or a bodypanel of the vehicle. In some cases, a portion of the vehicle chassismay comprise a material that may enhance a radar signal. A radar signalmay be enhanced if the strength of the signal is increased relative tothe noise of the signal.

The support structure may be able to decouple the one or moretransmitting and/or receiving antennas from vibrations, shocks, orimpacts experienced by a vehicle in motion. In some embodiments, thefixed spatial configuration may also be modified or controlled by amechanism configured to adjust and/or calibrate the alignment orlocation of one or more transmitting and/or receiving antennas. Themechanism may be an open loop control system, a closed loop controlsystem, a feedback loop system, a feedforward loop system, or anycombination thereof.

In some embodiments, the system may be a SAR system or a SAR-basedsystem as described elsewhere herein. The SAR system may include a radarantenna array. The radar antenna array may have a virtual antenna. Avirtual antenna may be an antenna and/or an antenna array that issimulated by a Synthetic Aperture Radar (SAR) system (or a SAR-basedsystem). A SAR system may operate similarly to a phased array radarsystem, but instead of many parallel antenna elements, a single antennamay be used to combine multiple raw radar returns from differentgeometric positions of a terrestrial vehicle into coherent focusedimages. A SAR system can provide high resolution radar imagery from amoving terrestrial platform or terrestrial vehicle in part by using themotion path of the platform or vehicle to simulate a large antenna oraperture electronically and/or virtually. In some embodiments, thevirtual antenna may be an antenna and/or an antenna array that issimulated by a multiple-input-multiple-output (MIMO) radar system (or aMIMO-based system). A MIMO radar system may use multiple transmittingantennas to transmit signals independently of other transmittingantennas, and multiple receiving antennas to receive signalsindependently of other receiving antennas. A MIMO radar system may usemultiple transmitting antennas M and multiple receiving antennas N tosimulate a virtual array of M×N transmitting and/or receiving antennas.In other embodiments, a virtual antenna may be an antenna and/or anantenna array that is simulated by a SAR-based system, a MIMO-basedsystem, or any system that includes one or more features of a SAR-basedsystem and/or a MIMO-based system.

As illustrated in FIG. 3A, the radar antenna array may have an effectivesensitivity pattern 115 associated with the radar antenna array. Theeffective sensitivity pattern may be a radiation pattern of the radarantenna array. A radiation pattern may be a pattern showing thedirectivity or gain of a radar antenna array as a function of azimuthand/or elevation angle. The directivity or gain of a radar antenna arraymay be determined in part by a ratio between the radiation intensity ofthe radar antenna array and the radiation intensity of an isotropicantenna. An isotropic antenna may be an antenna that is capable ofradiating or receiving energy uniformly in all directions. The radiationintensity may be a function of power radiated or received by the radarantenna array per unit solid angle. A solid angle may be a unit of areacorresponding to a portion of the surface area of a sphere. A radiationpattern may include one or more lobes. A lobe may be a region within theradiation pattern where the directivity or gain of the antenna attains alocal maximum value. A lobe may be oriented in any direction rangingfrom 0 degrees to 360 degrees in azimuth angle and/or elevation anglerelative to a pre-defined orientation of the radar antenna array. Thepre-defined orientation of the radar antenna array may be defined by anazimuth and/or elevation angle ranging from 0 degrees to 360 degreesrelative to the path of motion of the terrestrial vehicle.

As illustrated in FIG. 3A, the effective sensitivity pattern 115 mayinclude one or more side lobes 116-1, 116-2, 116-3, 116-4 and a mainlobe 117. A main lobe may be a lobe within the radiation pattern withthe largest directivity or gain relative to other lobes in the radiationpattern. A main lobe may indicate the presence of a target in adirection that the main lobe is oriented. A side lobe may be any lobethat is not a main lobe. A side lobe may represent a region of unwantedor unintended radiation. The side lobe may be an aliasing side lobe. Analiasing side lobe may be a side lobe with a directivity or gain thatapproaches the magnitude of the directivity or gain of a main lobe dueto aliasing effects during signal sampling. Aliasing effects may bedistortions or artifacts created when a signal is reconstructed fromsample signals. Aliasing may include spatial aliasing and/or temporalaliasing. Spatial aliasing may include the degradation of image shapes,definitions, and/or details that occurs due to limited spatialresolution. Temporal aliasing may include strobing or flickering effectsthat occur in an image due to limited temporal resolution.

Referring back to FIG. 1B, one or more controllers 130-1, 130-2, 130-3may be operatively coupled to a radar antenna arrays 110. The one ormore controllers may be configured to use a spatial configuration of theradar antenna array and spatial information of a terrestrial vehiclewhile the vehicle is in motion to generate an enhanced main lobe.Spatial information of a terrestrial vehicle may include informationabout the position, velocity, acceleration, and other kinematicproperties of the terrestrial vehicle relative to external targets, asurrounding environment, a radar antenna array, or any other static ormoving point of reference. As illustrated in FIG. 3B, an enhanced mainlobe 118 may be a main lobe that has increased in magnitude with respectto one or more side lobes 116-1, 116-2, 116-3, 116-4. An enhanced mainlobe may indicate the presence of a target in a direction that theenhanced main lobe is oriented. The enhanced main lobe may be generatedby attenuating one or more side lobes relative to the main lobe, or byenhancing the main lobe relative to one or more side lobes. Attenuationof one or more side lobes may be achieved by the use of a SAR imagingalgorithm. The SAR imaging algorithm may be an image formationalgorithm. An image formation algorithm may be an algorithm that cancreate two-dimensional (2D) or three-dimensional (3D) images of one ormore targets using a plurality of signals received by the radar antennaarray. The plurality of signals may contain data such as phasemeasurements at one or more transmitting and/or receiving antennas in aradar antenna array. An image formation algorithm may be a time domainalgorithm and/or a frequency domain algorithm. A time domain algorithmmay be an algorithm that constructs an image of one or more targets byperforming calculations with respect to the samples in time of theplurality of signals transmitted and/or received by the radar antennaarray. A frequency domain algorithm may be an algorithm that constructsan image of one or more targets by performing calculations with respectto a Fourier transform of the samples in time of the plurality ofsignals transmitted and/or received by the radar antenna array. Timedomain algorithms may include one or more features of a global backprojection algorithm, a fast back projection algorithm, a fastfactorized back projection algorithm, and/or a local back projectionalgorithm. Time domain algorithms may use a matched filtering process tocorrelate one or more radar pulses transmitted by the radar antennaarray and/or transmitting antenna with one or more signals received bythe radar antenna array and/or receiving antenna. Frequency domainalgorithms may include one or more features of a Fourier-domainreconstruction algorithm, chirp scaling algorithm, range migrationalgorithm, polar format algorithm, Omega-K algorithm, and/or aRange-Doppler algorithm. The one or more controllers may be furtherconfigured to use the enhanced main lobe to determine the spatialdispositions or characteristics of one or more targets.

Referring back to FIG. 2B, the radar antenna array 110 may have a fieldof detection 119 as previously described elsewhere herein. A field ofdetection may include a region relative to the radar antenna array wherethe radar antenna array may collect data. The field of detection mayinclude a distance, range, and/or a direction. For example, the field ofdetection may include a maximum distance and/or minimum distance thatcan be detected by the radar antenna array. The minimum distance may bezero. The maximum distance may or may not be affected by environmentalconditions (e.g., temperature, particulates in the air, precipitation,air pressure, noise, etc.). A direction may include an angle range. Forinstance, a radar antenna array may have an angular range field of view.The radar antenna array may not be capable of collecting data outsidethe field of detection. Areas outside the field of detection of a radarantenna array may be a blind spot of the radar antenna array and/orsystem.

Although various fields of detection are illustrated with variousshapes, it may be understood that the field of detection may have anyshape. For example, the field of detection may have a substantiallycircular shape. The vehicle may be located at the center of the circleor another part of the circle. The field of detection may have asubstantially ellipsoidal or oval shape. The field of detection may havea substantially sector or wedge shape. The field of detection may have asubstantially triangular shape, quadrilateral shape (e.g., rectangularshape, square shape, diamond shape, trapezoidal shape), pentagonalshape, hexagonal shape, octagonal shape, or any other shape. Any of theshapes described herein may represent a cross-section of the field ofdetection. In some embodiments, the shapes may be a lateralcross-sectional shape, or a vertical cross-sectional shape. The field ofdetection may form a spherical, semi-spherical, conical, cylindrical,prismatic, toroidal, or any other type of shape. In some embodiments,the field of detection may comprise a combination or a plurality of anyof the shapes described, to collectively form a new shape. The field ofdetection may be formed of a single continuous shape or multiplediscontinuous shapes. The field of detection may collectively reacharound at least 360 degrees surrounding the vehicle. In some instances,the field of detection may be at least about 15 degrees, 30 degrees, 45degrees, 60 degrees, 75 degrees, 90 degrees, 120 degrees, 150 degrees,180 degrees, 210 degrees, 240 degrees, 270 degrees, 300 degrees, or 330degrees around the vehicle. The field of detection may have angularvalues less than any of the values described herein, or falling within arange between any two of the values described herein. The angle rangesmay be provided relative to a lateral direction around the vehicle, orvertical direction around the vehicle. In some embodiments, the field ofdetection may be evenly distributed around the vehicle. In some cases,the field of detection may correspond to the effective sensitivitypattern associated with the radar antenna array.

In some embodiments, the spatial configuration of the radar antennaarray may be based at least in part on an imaging region and an angularresolution within a field of detection of the radar antenna array. Animaging region may be a subset of the region encompassed by the field ofdetection of the radar antenna array. The imaging region may include aregion within the field of detection of the radar antenna array that isdefined by a range of azimuth angles and/or a range of elevation angles.The imaging region may be a pre-defined design parameter. The imagingregion may be centered on the vehicle's direction of motion. In somecases, the imaging region may be defined separately for azimuth angleranges and elevation angle ranges. The imaging region may cover lessthan ±10 degrees from a forward or reverse direction of motion of aterrestrial vehicle. The imaging region may cover at least ±10 degreesfrom a forward or reverse direction of motion of a terrestrial vehicle.In other cases, the imaging region may cover no more than ±60 degreesfrom a forward or reverse direction of motion of a terrestrial vehicle.Alternatively, the imaging region may cover more than ±60 degrees from aforward or reverse direction of motion of a terrestrial vehicle. Theimaging region may cover the field of detection.

In some embodiments, the radar antenna array may comprise a radar systemused on a vehicle in motion. The radar system may be a SAR system, aSAR-based system, a MIMO system, a MIMO-based system, or any other radarsystem as described elsewhere herein. The vehicle in motion may move apre-defined distance L over a pre-defined time period T.

The radar antenna array may have an operating wavelength λ. Theoperating wavelength may be equivalent to the wavelength associated withthe center frequency f₀ of the successive radar pulses transmitted bythe radar antenna array and/or one or more transmitting antennascomprising the radar antenna array.

The radar antenna array may have an angular resolution. The angularresolution may be an azimuth resolution or an elevation resolution, orany combination thereof. Azimuth resolution may be the ability of aradar system to distinguish between two or more targets at similar rangebut different bearings. Elevation resolution may be the ability of aradar system to distinguish between two or more targets at similar rangebut different elevation. Azimuth and elevation resolution may be afunction of radar antenna array geometry. The angular resolution of theradar antenna array may be given by:

$\theta = {2\sqrt{\frac{\lambda}{2L}}}$

where θ is the angular resolution of the radar antenna array, λ is anoperating wavelength of the radar antenna array, and L is a pre-defineddistance parameter corresponding to a distance travelled by a vehicle. Lmay be the distance travelled by a vehicle over a period of time T. Tmay be a pre-defined time period. L and T may be design parameterschosen based on the accuracy of a radar antenna array and/or theaccuracy of a vehicle position sensor. In some cases, the one or morecontrollers of the system may be further configured to use the angularresolution of the radar antenna array and the operating wavelength ofthe radar antenna array at least in part to define a distance travelledby a terrestrial vehicle.

The radar system may be configured to combine a plurality of signalsreceived by the radar antenna array over a time period T to provide aneffective aperture of the radar antenna array. The effective aperturemay be proportional to √{square root over (L)}. The aperture size may be1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 10 cm, 100cm, 1 m, or any value between 1 mm and 1 m.

The radar antenna array may have an aperture size. In some embodiments,the aperture size may be based at least in part on the angularresolution of the radar antenna array and the operating wavelength ofthe radar antenna array. The relationship between aperture size, angularresolution, and operating wavelength may be given by:

$\theta = {c*\frac{\lambda}{A}}$

where θ is the angular resolution of the radar antenna array, c is aproportionality constant, λ is an operating wavelength of the radarantenna array, and A is the aperture size of the radar antenna array.

As shown in FIG. 4, in some embodiments, the one or more sidelobes 116may be located at an angular distance α from the main lobe 117. Theangular distance may range from 0 degrees to 360 degrees. In otherembodiments, the spatial configuration of the radar antenna array mayfurther include a spacing between adjacent transmitting and/or receivingantennas of the radar antenna array. The spacing may be a relative fixeddistance as described elsewhere herein. In some cases, the spatialconfiguration of the radar antenna array and/or the spacing betweenadjacent transmitting and/or receiving antennas may allow the angulardistance α between one or more sidelobes 116 and a main lobe 117 to begreater than the range of azimuth and/or elevation angles defining animaging region 150. In some cases, the spacing between adjacenttransmitting and/or receiving antennas may allow the one or more sidelobes to lie outside of the range of azimuth and/or elevation anglesdefining an imaging region. In any one or more of the embodimentsdescribed herein, the spacing between adjacent transmitting and/orreceiving antennas may be at least 10% greater than one-half of theoperating wavelength of the radar antenna array. In any of theembodiments described herein, the spacing between adjacent transmittingand/or receiving antennas may be greater than about 2 mm.

Referring back to FIG. 1B, one or more controllers 130-1, 130-2, 130-3may be operatively coupled to a radar antenna arrays 110. The one ormore controllers may be configured to use spatial information of aterrestrial vehicle and a spatial configuration of the radar antennaarray to provide an enhanced main lobe. The one or more controllers mayprovide an enhanced main lobe by attenuating one or more side lobesrelative to a main lobe, or by enhancing a main lobe relative to one ormore side lobes. Spatial information of a terrestrial vehicle mayinclude a distance traveled by the terrestrial vehicle. The spatialconfiguration of the radar antenna array may include a spacing betweenadjacent transmitting and/or receiving antennas as described elsewhereherein. In some embodiments, the spatial configuration of the radarantenna arrays may include a spacing between adjacent transmittingand/or receiving antennas in a radar antenna array. In some cases, thespacing may be greater than one-half of an operating wavelength of aradar antenna array.

Referring back to FIG. 2A, a radar antenna array may be configured totransmit successive radar pulses 105 at a pulse repetition frequency asdescribed elsewhere herein. In some embodiments, when the vehicle is inmotion, the distance traveled by the terrestrial vehicle between twosuccessive radar pulses may be a fraction of an operating wavelength ofthe radar antenna array. A fraction of the operating wavelength may beless than or equal to about 1, 0.75, 0.67, 0.5, 0.33, 0.25, 0.2, or 0.1of the operating wavelength. In some cases, a fraction of the operatingwavelength described herein may be greater than 1. For example, afraction of the operating wavelength may be at least about 1.25, 1.5,1.75, 2, 3, 4, 5, 6, 7, 8, 9, or 10 times the operating wavelength. Insome cases, the distance travelled by the terrestrial vehicle betweentwo successive radar pulses may be less than about one-half of theoperating wavelength of the radar antenna array.

FIG. 5 shows a controller 130 operatively coupled to a radar antennaarray 110 and a vehicle position sensor 120. In some embodiments, one ormore controllers may be configured to obtain position information of aterrestrial vehicle using a vehicle position sensor. A vehicle positionsensor may include any sensor that can obtain the spatial disposition ofa terrestrial vehicle. In some embodiments, the vehicle position sensormay include a global positioning system (GPS) sensor 121, an inertialmeasurement unit (IMU) 122, a camera 123, a LIDAR 124, a radar 125, awheel encoder 126, or any other sensor that may be used to monitor theposition of a moving object. Position sensors may include locationsensors (e.g., global positioning system (GPS) sensors, mobile devicetransmitters enabling location triangulation), vision sensors (e.g.,imaging devices capable of detecting visible, infrared, or ultravioletlight, such as cameras), proximity or range sensors (e.g., ultrasonicsensors, lidar, time-of-flight or depth cameras), inertial sensors(e.g., accelerometers, gyroscopes, inertial measurement units (IMUs)),altitude sensors, attitude sensors (e.g., compasses), pressure sensors(e.g., barometers), audio sensors (e.g., microphones) or field sensors(e.g., magnetometers, electromagnetic sensors). In some embodiments, thevehicle position sensor may be located onboard the terrestrial vehicleand situated separately from the radar antenna array. In some cases, thevehicle position sensor may be configured to be mounted to a front side,rear side, or lateral side of a terrestrial vehicle. The vehicleposition sensor may be mounted to any side of the vehicle, or to one ormore sides of the vehicle, e.g. a front side, rear side, lateral side,top side, and/or bottom side of the vehicle. In some cases, the vehicleposition sensor may be mounted between two or more adjacent sides of thevehicle.

In any of the embodiments described herein, the controller may beconfigured to determine spatial dispositions or characteristics of oneor more targets. The controller may determine the spatial dispositionsor characteristics of one or more targets by providing one or moreenhanced main lobes. The controller may be configured to provide one ormore enhanced main lobes by attenuating one or more side lobes and/orenhancing one or more main lobes. As shown in FIG. 6, the one or moreenhanced main lobes 118-1, 118-2, 118-3 in an effective sensitivitypattern 115 may be associated with the one or more targets 102-1, 102-2,102-3. In any one or more of the embodiments described herein, thecontroller may be further configured to differentiate between thespatial disposition and/or characteristics of the one or more targetsafter attenuating one or more side lobes and/or enhancing one or moremain lobes. Differentiating between the spatial dispositions orcharacteristics of the one or more targets may involve associatingand/or correlating one or more spatial dispositions or characteristicswith one or more distinct targets.

Various methods for identifying a position of a target are describedherein. The methods may be implemented using any one or more systemsdescribed elsewhere herein. In some embodiments, the system may beconfigured to perform a method for identifying a position of a target.The method may comprise collecting radar data from an environmentexternal to a terrestrial vehicle using a radar antenna array andcollecting position information of a terrestrial vehicle. The radar datamay include a main lobe and/or one or more sidelobes. The positioninformation of a terrestrial vehicle may be collected using a vehicleposition sensor. The one or more sidelobes may be an aliasing sidelobe.The method may further comprise using at least the position informationto generate an enhanced main lobe. The enhanced main lobe may begenerated by attenuating the one or more side lobes or by enhancing themain lobe relative to the one or more side lobes. The method may furthercomprise using the enhanced main lobe to identify a position of one ormore targets in an external environment with an accuracy of at least90%. In some cases, the target may have a cross-sectional size of atleast 0.2 meters. In some cases, the target may be located a distance ofat least 1 meter from any one or more sides of a terrestrial vehicle. Insome embodiments, the radar antenna array may be provided on a frontside of a terrestrial vehicle in a forward-facing direction of theterrestrial vehicle. In other embodiments, the radar antenna array maybe provided on a rear side of a terrestrial vehicle in a reverse-facingdirection of the terrestrial vehicle.

In some embodiments, the system may be configured to perform a methodfor determining a spatial disposition or a characteristic of a target.The method may comprise providing a radar antenna array on a terrestrialvehicle. The radar antenna array may be configured to be mounted to afront side, rear side, or lateral side of a terrestrial vehicle. Theradar antenna array may be mounted to any side of the vehicle, or to oneor more sides of the vehicle, e.g. a front side, rear side, lateralside, top side, and/or bottom side of the vehicle. In some cases, theradar antenna array may be mounted between two or more adjacent sides ofthe vehicle. The method may further comprise transmitting successiveradar pulses and receiving a plurality of signals corresponding to atleast a subset of the successive radar pulses with the aid of the radarantenna array. The plurality of signals may be generated upon the atleast a subset of the successive radar pulses interacting with thetarget. An effective sensitivity pattern associated with the radarantenna array may be obtainable from the plurality of signals. Theeffective sensitivity pattern may comprise a main lobe and one or moreside lobes. The one or more side lobes may comprise an aliasing sidelobe. The method may further comprise using position information of theterrestrial vehicle while the vehicle is in motion and a spatialconfiguration of the radar antenna array to provide an enhanced mainlobe. An enhanced main lobe may be provided by attenuating the side loberelative to the main lobe and/or enhancing the main lobe relative to theside lobe. Attenuation of one or more side lobes may be achieved by theuse of a SAR imaging algorithm. The SAR imaging algorithm may be animage formation algorithm as described elsewhere herein. The method mayfurther comprise using the enhanced main lobe to determine the spatialdispositions or characteristics of one or more targets. In someembodiments, the spatial disposition or characteristic of the target maybe determined substantially in real time while the terrestrial vehicleis in motion relative to the target. In some embodiments, the radarantenna array may be mounted on the terrestrial vehicle in aforward-facing direction or in a rear-facing direction relative to thedirection of motion of the terrestrial vehicle. In some cases, thespatial configuration of the radar antenna array may comprise a spacingbetween adjacent transmitting and/or receiving antennas of the radarantenna array as described elsewhere herein. The spacing may be greaterthan one-half of an operating wavelength of the radar antenna array. Insome embodiments, the method may further comprise determining a spatialdisposition or characteristic of a plurality of targets. The spatialdisposition or characteristic of a plurality of targets may bedetermined by attenuating one or more side lobes in the effectivesensitivity pattern or by enhancing one or more main lobes in theeffective sensitivity pattern to provide a plurality of enhanced mainlobes. The plurality of targets may comprise the target. In someembodiments, the method may further comprise differentiating between thespatial dispositions or characteristics of the plurality of targetsafter the plurality of side lobes have been attenuated or the pluralityof main lobes have been enhanced. Differentiating between the spatialdispositions or characteristics of the plurality of targets may involveassociating and/or correlating one or more spatial dispositions orcharacteristics with one or more distinct targets.

Computer control systems are provided herein that can be used toimplement methods or systems of the disclosure. FIG. 7 shows a computersystem 701 that is programmed or otherwise configured to implement amethod for determining a spatial disposition or characteristic of one ormore targets external to a vehicle. The computer system 701 can beconfigured to use spatial information of a terrestrial vehicle while thevehicle is in motion and a spatial configuration of a radar antennaarray to generate an enhanced main lobe. The computer system 701 maygenerate an enhanced main lobe by enhancing a main lobe in an effectivesensitivity pattern associated with the radar antenna array orattenuating one or more side lobes in an effective sensitivity patternassociated with the radar antenna array. The computer system 701 may usethe enhanced main lobe to determine a spatial disposition orcharacteristic of one or more targets external to a vehicle. Thecomputer system 701 can be an electronic device of a user or a computersystem that is remotely located with respect to the electronic device.The electronic device can be a mobile electronic device.

The computer system 701 includes a central processing unit (CPU, also“processor” and “computer processor” herein) 705, which can be a singlecore or multi core processor, or a plurality of processors for parallelprocessing. The computer system 701 also includes memory or memorylocation 710 (e.g., random-access memory, read-only memory, flashmemory), electronic storage unit 715 (e.g., hard disk), communicationinterface 720 (e.g., network adapter) for communicating with one or moreother systems, and peripheral devices 725, such as cache, other memory,data storage and/or electronic display adapters. The memory 710, storageunit 715, interface 720 and peripheral devices 725 are in communicationwith the CPU 705 through a communication bus (solid lines), such as amotherboard. The storage unit 715 can be a data storage unit (or datarepository) for storing data. The computer system 701 can be operativelycoupled to a computer network (“net-work”) 730 with the aid of thecommunication interface 720. The network 730 can be the Internet, aninternet and/or extranet, or an intranet and/or extranet that is incommunication with the Internet. The network 730 in some cases is atelecommunication and/or data network. The network 730 can include oneor more computer servers, which can enable distributed computing, suchas cloud computing. The network 730, in some cases with the aid of thecomputer system 701, can implement a peer-to-peer network, which mayenable devices coupled to the computer system 701 to behave as a clientor a server.

The CPU 705 can execute a sequence of machine-readable instructions,which can be embodied in a program or software. The instructions may bestored in a memory location, such as the memory 710. The instructionscan be directed to the CPU 705, which can subsequently program orotherwise configure the CPU 705 to implement methods of the presentdisclosure. Examples of operations performed by the CPU 705 can includefetch, decode, execute, and writeback.

The CPU 705 can be part of a circuit, such as an integrated circuit. Oneor more other components of the system 701 can be included in thecircuit. In some cases, the circuit is an application specificintegrated circuit (ASIC).

The storage unit 715 can store files, such as drivers, libraries andsaved programs. The storage unit 715 can store user data, e.g., userpreferences and user programs. The computer system 701 in some cases caninclude one or more additional data storage units that are external tothe computer system 701, such as located on a remote server that is incommunication with the computer system 701 through an intranet or theInternet.

The computer system 701 can communicate with one or more remote computersystems through the network 730. For instance, the computer system 701can communicate with a remote computer system of a user (e.g., an enduser, a vehicle operator, a vehicle passenger, a vehicle manufacturer,etc.). Examples of remote computer systems include personal computers(e.g., portable PC), slate or tablet PC's (e.g., Apple® iPad, Samsung®Galaxy Tab), telephones, Smart phones (e.g., Apple® iPhone,Android-enabled device, Blackberry®), or personal digital assistants.The user can access the computer system 701 via the network 730.

Methods as described herein can be implemented by way of machine (e.g.,computer processor) executable code stored on an electronic storagelocation of the computer system 701, such as, for example, on the memory710 or electronic storage unit 715. The machine executable or machinereadable code can be provided in the form of software. During use, thecode can be executed by the processor 705. In some cases, the code canbe retrieved from the storage unit 715 and stored on the memory 710 forready access by the processor 705. In some situations, the electronicstorage unit 715 can be precluded, and machine-executable instructionsare stored on memory 710.

The code can be pre-compiled and configured for use with a machinehaving a processer adapted to execute the code, or can be compiledduring runtime. The code can be supplied in a programming language thatcan be selected to enable the code to execute in a pre-compiled oras-compiled fashion.

Aspects of the systems and methods provided herein, such as the computersystem 701, can be embodied in programming. Various aspects of thetechnology may be thought of as “products” or “articles of manufacture”typically in the form of machine (or processor) executable code and/orassociated data that is carried on or embodied in a type of machinereadable medium. Machine-executable code can be stored on an electronicstorage unit, such as memory (e.g., read-only memory, random-accessmemory, flash memory) or a hard disk. “Storage” type media can includeany or all of the tangible memory of the computers, processors or thelike, or associated modules thereof, such as various semiconductormemories, tape drives, disk drives and the like, which may providenon-transitory storage at any time for the software programming. All orportions of the software may at times be communicated through theInternet or various other telecommunication networks. Suchcommunications, for example, may enable loading of the software from onecomputer or processor into another, for example, from a managementserver or host computer into the computer platform of an applicationserver. Thus, another type of media that may bear the software elementsincludes optical, electrical and electromagnetic waves, such as usedacross physical interfaces between local devices, through wired andoptical landline networks and over various air-links. The physicalelements that carry such waves, such as wired or wireless links, opticallinks or the like, also may be considered as media bearing the software.As used herein, unless restricted to non-transitory, tangible “storage”media, terms such as computer or machine “readable medium” refer to anymedium that participates in providing instructions to a processor forexecution.

Hence, a machine readable medium, such as computer-executable code, maytake many forms, including but not limited to, a tangible storagemedium, a carrier wave medium or physical transmission medium.Non-volatile storage media include, for example, optical or magneticdisks, such as any of the storage devices in any computer(s) or thelike, such as may be used to implement the databases, etc. shown in thedrawings. Volatile storage media include dynamic memory, such as mainmemory of such a computer platform. Tangible transmission media includecoaxial cables; copper wire and fiber optics, including the wires thatcomprise a bus within a computer system. Carrier-wave transmission mediamay take the form of electric or electromagnetic signals, or acoustic orlight waves such as those generated during radio frequency (RF) andinfrared (IR) data communications. Common forms of computer-readablemedia therefore include for example: a floppy disk, a flexible disk,hard disk, magnetic tape, any other magnetic medium, a CD-ROM, DVD orDVD-ROM, any other optical medium, punch cards paper tape, any otherphysical storage medium with patterns of holes, a RAM, a ROM, a PROM andEPROM, a FLASH-EPROM, any other memory chip or cartridge, a carrier wavetransporting data or instructions, cables or links transporting such acarrier wave, or any other medium from which a computer may readprogramming code and/or data. Many of these forms of computer readablemedia may be involved in carrying one or more sequences of one or moreinstructions to a processor for execution.

The computer system 701 can include or be in communication with anelectronic display 735 that comprises a user interface (UI) 740 forproviding, for example, a portal for monitoring one or more targetsdetected by the system. A user can use the portal to view informationrelating to the spatial disposition or characteristics of one or moretargets detected by the system. The portal may be provided through anapplication programming interface (API). A user or entity can alsointeract with various elements in the portal via the UI. Examples ofUI's include, without limitation, a graphical user interface (GUI) andweb-based user interface.

Methods and systems of the present disclosure can be implemented by wayof one or more algorithms. An algorithm can be implemented by way ofsoftware upon execution by the central processing unit 705. Thealgorithm may be configured to obtain spatial information of aterrestrial vehicle. The algorithm may be further configured to use thespatial information of a terrestrial vehicle and a spatial configurationof a radar antenna array to generate an enhanced main lobe. The enhancedmain lobe may be generated by attenuating one or more side lobes in aneffective sensitivity pattern associated with the radar antenna arrayrelative to a main lobe in an effective sensitivity pattern associatedwith the radar antenna array, or by enhancing the main lobe relative tothe one or more side lobes. The algorithm may be further configured touse the enhanced main lobe to determine a spatial disposition orcharacteristic of one or more targets external to a vehicle.

While preferred embodiments of the present invention have been shown anddescribed herein, it will be obvious to those skilled in the art thatsuch embodiments are provided by way of example only. Numerousvariations, changes, and substitutions will now occur to those skilledin the art without departing from the invention. It should be understoodthat various alternatives to the embodiments of the invention describedherein may be employed in practicing the invention. It is intended thatthe following claims define the scope of the invention and that methodsand structures within the scope of these claims and their equivalents becovered thereby.

What is claimed is:
 1. A system for determining a spatial disposition or a characteristic of a target, said system comprising: a radar antenna array mountable on a terrestrial vehicle, wherein said radar antenna array is configured to (i) transmit successive radar pulses, and (ii) receive a plurality of signals corresponding to at least a subset of said successive radar pulses, which plurality of signals is generated upon the at least said subset of said successive radar pulses interacting with said target, wherein an effective sensitivity pattern associated with said radar antenna array is obtainable from said plurality of signals, said effectivity sensitivity pattern comprising a main lobe and a side lobe, wherein said side lobe comprises an aliasing side lobe; and at least one controller operatively coupled to said radar antenna array, wherein said at least one controller is configured to (i) use spatial information of said terrestrial vehicle while said terrestrial vehicle is in motion and a spatial configuration of said radar antenna array to attenuate said side lobe relative to said main lobe or enhance said main lobe relative to said side lobe, thereby providing an enhanced main lobe, and (ii) use said enhanced main lobe to determine said spatial disposition or said characteristic of said target. 